One type of isocyanate coating is made from isocyanate-terminated adducts or prepolymers cured with a second component as a catalyst. Crosslinking is assumed to occur through the formation of substituted urea groups by reaction of the terminal NCO groups with the moisture in the air as well as through the formation of biuret and allophanate linkages. The latter crosslinks may be formed by the catalyzed reaction of the isocyanate groups with urea and urethane linkage.
Two component isocyanate base coatings include the reaction of isocyanates with hydroxy groups cured with the presence of an organometallic catalyst or the use of isocyanate groups catalyzed by organic amines preferably tertiary amines.
Certain high molecular weight amines have been suggested as catalysts for isocyanates in the presence of polyol in the preparation of urethane foam (e.g., see U.S. Pat. Nos. 3,428,708 and 3,448,065).